Guide to Using Water Soluble Fertilizers

Water Soluble Fertilizers (WSF) are a great source of nutrients to use for growing indoor hydroponic crops. WSF products, such as General Hydroponics® FloraPro®, are fertilizer blends produced from high quality, technical grade fertilizer salts in dry, powder form. WSF’s are meant to be dissolved, or solubilized, in water before use.

Dissolving WSF fertilizers may be a new experience for some growers

Starting Tips

Historically, indoor hydroponic growers relied on liquid fertilizer products. For those growers who have always used liquids and want to use WSFs in their production, there are a few things that need to be kept in mind when using Hawthorne WSF products.

Water quality is important.

Reverse Osmosis (RO) water is preferred but not required. If not using RO water and using an outside source, it’s best to have a water analysis conducted by a reputable lab to assure there are no contaminants that will interact with your fertilizer program.

Use hot water if possible.

Dissolving fertilizer salts is an endothermic process. That means that dissolving any fertilizer salt will need energy (i.e. stirring or heat) to make the process go faster. When making either dilute or concentrated solutions, starting with hot water and agitation, speeds up the process up considerably. The speed in which a fertilizer dissolves is driven by the amount to be dissolved, the temperature of the water used and the amount of agitation employed.